Insulator



(No Model.) 2 SheetsSheet 1.

- L. MQOARTHY.

INSULATOR No. 530,706. Patented'Dec. 11, 1894.

E'EILCIYL.

1241/ '5 Mama- (No Model.) 2 Sheets-Sheet 2.

L. MCCARTHY.

INSULATOR.

No. 530,706. Patented Dec. 11, 1894.

m e M lgyzivesses UNITED STATES PATENT OFFICE.

LOUIS MCCARTHY, OF BOSTON, MASSACHUSETTS.

INSULATOR.

SPECIFICATION forming part of Letters Patent No. 530,706, dated December 11, 1894.

Application filed September 18, 1894. Serial No. 523,372. (No model.)

To all whom it may concern.-

Be it known that I, LoUIs MCCARTHY, a citizen of the United States, residing at Boston, in the county of Sulfolk and State of Massachusetts, have invented certain new and useful Improvements in Insulators, of which the following is a specification, reference being had therein to the accompanying drawings.

My invention relates to electrical insulators, and more especially to insulators of the kind which are known as pole insulators.

My invention is fully set forth in the following description, and the novel features thereof are pointed out in the claims which are appended hereto and made a part hereof.

In the accompanying drawings, to which reference is made in the following description, I have shown in Figure 1 a perspective of an insulator embodying myinvention, the lower portion thereof being represented in section to show the construction more fully. Fig. 2 shows in perspective an insulator embodying myinvention and having a modified form of clip for securing the conductor in place. Fig. 3 is a perspective showing a modification, the lower portion of the insulator being represented in section.

It is very desirable that pole insulators, which are generally used in outdoor constructions, should be strong and durable, while at the same time they should afford a maximum degree of insulation. The exterior portions of such insulators usually are formed of metal in order to secure strength, there being employed an exterior metal shell and an interior body or mass of insulating material. The latter frequently consists of one of the well known insulating compositions which may be molded While in a plastic condition, and which will then set and harden. Inasmuch as these insulators, as above stated, generally, are used out of doors, and are exposed to rain and snow, difficulty has been experienced in preventing the bridging of the surface of the insulating material or composition between the lower exposed portion of the shell and the insulator support, by the collection of moisture on said surface.

The chief aim of the present invention is to provide againstthe difficulty just mentioned, and to reduce to a minimum the danger of bridging. To this end, I continue the interior body or mass of insulating material down below the lower edge of the metallic shell aforesaid, and, in addition to embedding the said lower edge in the insulating material, I cover a greater or less portion of the exterior of the shell with insulating material continuous with the said interior body or mass. This is clearly shown in the drawings, in which the metallic shell aforesaid is designated A, and the insulating material 5. The lower portion of the metallic shell is designated 3, and, as above indicated, is wholly embedded in the insulating material. Figs. 1 and 2 show the insulating material 5 covering the exterior of the shell only for a short portion of the length of the shell, While Fig. 3 shows the said material as extending to the clip which is provided at the upper end of the insulator.

Inasmuch as in the case of my improved construction both the exterior and interior surfaces of the skirt, as well as the lower edge of the latter, are composed of insulating material, the danger of bridging in consequence of the collection of moisture is reduced to a minimum.

To the end that the exterior casing of insulating material, applied as set forth above, may not chip off, or become detached, and thereby to render such casing as nearly equal as possible to a metallic exterior, I make perforations 4 at intervals in the metallic shell, through which the composition flows, thereby enabling the portions of the latter on the opposite surfaces of the metal shell to become bound together at intervals. These perforations enable the insulating material to secure itself very firmly in place, and assist in obtaining a durable skirt or lower edge.

At 1, in Figs. 1 and 2, is an outwardly projecting portion or flange on the lower portion of the metallic shell, its under surface forming ashoulder 2 located outside the downwardly projecting edge portion 3 of the shell. Certain of the perforations 4 are made in the said edge portion 3 adjacent to the said shoulder 2, as shown. The insulating material 5 is molded against the said shoulder, giving an improved finish, and protecting the upper portion of the insulating material.

For the purpose of securingthe cable orconductor on the insulator, I have shown two forms of clip or securing device. The form shown in Figs. 1 and 3 has a trough-shaped base or bed 8, curved slightly from end to end and provided at each side with two or more upwardly projecting retaining portions 7, which are designed to be bent over the conductor to secure it in the bed 8. The projections 7 are preferably set alternately, that is, a projection on one side is opposite a space between the projections on the other side.

In Fig. 2 I have shown a form of clip which consists of a grooved bed portion 9 corresponding with the portion 8 of the form shown in Figs. 1 and 3, and provided with a cover or securing portion 10, which latter at one side is provided with an eye not shown, which engages with a projection, not shown, on the part 9, and at the other side is provided with a lug 11 which corresponds with a lug 12 on the part 9. A bolt 13 is provided which is passed through a hole in the lugs 11 and 12 and is secured therein by means of a nut let which screws onto the end of said bolt. This form of clip is of durable construction and may be readily opened and closed to release or secure the conductor. its construction is fully shown and described in my Letters Patent No. 520,937, granted June 5, 1894.

The insulator is simple and inexpensive in construction, and is durable and efficient in operation.

What I claim is 1. An insulator comprising a metallic case having a downwardly projecting skirt with perforations therein, and a mass of insulating material applied to both the interior and exterior as well as the edge of said skirt and passing through said perforations, the edge portion of said skirt being embedded in the insulating material, substantially as described.

2. An insulator comprising a metallic case having at the lower edge thereof a downwardly projecting portion or skirt with perforations therein, a shoulder on the proximate portion of the said metallic case, and a mass of insulating material in which said downwardly projecting portion of the skirt is embedded and which is molded against the said shoulder, substantially as described.

In testimony whereofI affix my signature in presence of two witnesses.

LOUIS MCCARTHY.

Witnesses:

WM. A. MAOLEOD, CHAS. F. RANDALL. 

